Studies are being conducted to elucidate the developmental interrelationships of putative neurotransmitters, catecholamines, serotonin, acetylcholine and GABA in the brain. The metabolism of neurotransmitters will be altered at specific periods of neurochemical maturation during gestational or neonatal stages by (1) placement of discrete lesions in the nuclei of origin of neurons containing dopamine, norepinephrine, serotonin, acetylcholine or GABA in 1-3, 10, 21 and 39 day old rats; (2) neonatal or intraventricular injections of 6-hydroxydopamine; and (3) with the use of neuroleptic drugs that are known to act by blocking dopamine receptors. The hypothesis that the manipulation of biochemical and morphological differentiation during gestational or neonatal stages of growth has long-lasting and/or permanent consequences on normal neurochemistry of brain will be tested.